Table 1.

Electrocardiographic abnormalities in the inherited arrhythmia syndromes

Syndrome	ECG features
Long QT syndrome7	QTc ≥ 500 ms in the absence of other causes LQT2—notched/bifid T wave LQT3—long isoelectric ST segment
Brugada syndrome8	Right bundle branch block and ST elevation in right precordial leads Type I—coved ST elevation ≥2 mma Types II and III—saddleback pattern
Catecholaminergic polymorphic VT8	Classic bidirectional VT during exercise
Short QT syndrome8	QTc ≤ 330 ms or QTc < 360 ms with genetic mutation, aborted SCD or family history
Arrhythmogenic right ventricular dysplasia/cardiomyopathy9	T wave inversion in right precordial leads Epsilon wave
Hypertrophic cardiomyopathy10	ECG-LVH; ST-T wave abnormalities
Early repolarization syndrome8	J-point elevation ≥1 mm in ≥2 contiguous inferior and/or lateral leads ‘Benign’ pattern: ascending ST segment ‘Malignant’ pattern: horizontal/descending ST segment

VT, ventricular tachycardia; SCD, sudden cardiac death; LVH, left ventricular hypertrophy.

^aProvocative testing with sodium channel blockers can unmask type I pattern in those with normal ECG or type II/III pattern at baseline.